1. Field of the Invention
The present invention generally relates to a bending machine used for bending a tube or pipe made of metal or the like. More specifically, the invention relates to a bending machine capable of efficiently proceeding a bending operation without collapsing the tube.
2. Description of the Prior Art
A tube made of metal is such as of use in a fuel supply system or exhaust system of an automobile engine. This kind of tube is manufactured by bending a long metal tube having a circular cross-section so as to obtain a desired shape since a desired specified arrangement of the tube is necessary so as not to interfere with structural members and other parts of a body of the automobile. A conventional bending machine used for bending operation is shown in FIG. 12.
This bending machine 1 is provided with a roll-shaped bending die 7 and a clamp die 9 for clamp a tube 3 onto the roll-shaped bending die 7. The pressure die 11 presses the periphery of the tube 3 and moves in a direction of arrow A to rotate the bending die 7 in a direction of arrow B to pull the tube 3 around the peripheral surface of the bending die 7. The clamp die 9 is retractable in directions of arrows C and D along a guiding base 13 connected to the bending die 7. The clamp die 9 which is clamping the tube 3 with the cooperation of the bending die 7 is enable to rotate in a direction of arrow B. A groove 15 having a arc-shaped cross-section and corresponding to the outer surface of the tube is formed in the outer periphery of the bending die 7. Pressure contact surfaces of the clamp die 9 and the tube presser 11 have Similar grooves 17 and 19 adapted for contacting the tube 3.